In a conventional image forming apparatus, a process cartridge type is employed in which the photosensitive drum and process means actable on the photosensitive drum and the developing roller are unified into a cartridge which is detachably mountable to the main assembly of the image forming apparatus.
With the process cartridge type, maintenance operations for the image forming apparatus can be carried out by the user without relying on a service person, and therefore, the operationality is remarkably improved.
For this reason, the process cartridge type is widely used in the image forming apparatuses.
Japanese Laid-open Patent Application 2008-233867, for example, discloses a process cartridge which is usable an electrophotographic image formation type electrophotographic image forming apparatus and which is capable of being mounted and dismounted relative to a main assembly of the electrophotographic image forming apparatus provided with a driving shaft, in a direction substantially perpendicular to an axis of the driving shaft.